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With the help of NASA's Hubble Space Telescope, astronomers have discovered that violent, or superfluous, red dwarf stars could affect the livability of planets in orbit around it.
The results of the study published in the Astrophysical Journal show that young small-mass stars shine much more frequently and energetically than the ancient stars and stars of the Middle Ages like our Sun.
The results are based on observations of the flare frequency of 12 red dwarfs.
Hubble observes such stars as part of a larger program called HAZMAT – Living Areas and Dwarves' Activity Across Time.
"M dwarf" is the astronomical term for a red dwarf star – the smallest, most abundant and most enduring star type in our galaxy.
The HAZMAT program is an ultraviolet study of red dwarfs at three different ages – young, intermediate and old.
"The goal of the HAZMAT program is to help understand the livability of the planets around low-mass stars," explained the program's lead researcher, Evgenya Shkolnik of the University of Hawaii. # 39; Arizona.
"These low-mass stars are of paramount importance for the understanding of planetary atmospheres," Shkolnik added.
Stellar eruptions of red dwarfs are particularly bright in ultraviolet wavelengths, compared to stars similar to those of the Sun.
The ultraviolet sensitivity of Hubble makes the telescope very useful for observing these flares.
Eruptions are thought to be fed by intense magnetic fields that become entangled by the swirling motions of the stellar atmosphere.
When entanglement becomes too intense, the fields break and reconnect, releasing huge amounts of energy.
The team found that the eruptions of the youngest red dwarves studied – about 40 million years ago – were 100 to 1,000 times more energetic than when the stars were older.
It is at this age that terrestrial planets form around their stars.
About three-quarters of the stars in our Milky Way galaxy are red dwarfs. Most planets "habitable areas" of the galaxy – planets orbiting their stars at a distance where the temperatures are moderate enough to let liquid water on their surface – red dwarfs in orbit.
In fact, the closest star to our Sun, a red dwarf named Proxima Centauri, has a planet the size of the Earth in its habitable zone.
However, red dwarfs, especially young red dwarfs, are active stars. They produce eruptions that could release so much energy that it disrupts and eventually destroys the atmosphere of these nascent planets.
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